Process of making alkali hydrosulfites.



UNITED STATES RANT FTC.

BERNHARD DEUTECOM, OF LEVERKUSEN, NEAR COLOGNE, GERMANY, ASSIGNOR TOFARBENFABRIKEN VOBM. FRIEDR. BAYER & (10., OF ELBERFELD, G-ERHEANY, A

CORPORATION OF GERMANY.

PROCESS OF MAKING ALKALI HYDROSULFITES.

No Drawing.

new and useful Improvements in Processes of Making Alkali Hydrosulfites,of which the following is a specification.

I have found that while sodium hydrosulfite is scarcely soluble inammonia, hydrosulfite compounds of zinc, especially zinc hydrosulfite,its double salts; e. g. Zinc sodium hydrosulfite and its complexcompounds; 6. g. zinc hydrosulfite ammonium c'hlorid, are easily solublein it. From such a concentrated ammoniacal solution, the sodium orpotassium hydrosulfite is precipitated if such sodium or potassiumcompounds as sodium chlorid, potassium chlorid, acetate of sodium,acetate of potassium, etc. are added. Generally speaking, alkali saltsof acids which form zinc salts soluble in ammonia water, preferablycontaining an excess of ammonia, may be employed for this precipitation.They are used in a quantity equivalent to the hydrosulfurous acidcontained in the solution.

On using zinc sodium hydrosulfite, of course only such a quantity of thealkali compound needs to be added as is equivalent to the zinc.

If the alkali compound is added in solution it is advisable in order toaccelerate the precipitation of the alkali hydrosulfite to seed thesolution, that is to introduce a very small quantity of a crystal of asolid sodium or potassium compound 6. g. NaOH,

Specification of Letters Patent.

Application filed November 3, 1908.

Patented Sept. 28, 1909.

Serial No. 460,971.

01K, ClNa. The hydrosulfite thus obtained is practically free from Zincor other salts and byproducts.

The reaction, which must be carried out at temperatures below (3., as athigher temperatures hydrosulfites are decomposed, probably proceedsaccording to the following formulae:

The process above described has the ad vantage that the alkalihydrosulfite is at once obtained in a solid state without the costlyprocess of having to evaporate its solution, While the zinc remainsdissolved.

The process of producing alkali hydrosulfites from hydrosulfitecompounds of Zinc, Which process consists in dissolving the latter saltsin ammonia, treating this solution with an alkali salt of an acid whichforms salts of Zinc soluble in ammonia water and isolating the alkalihydrosulfites which are thus caused to crystallize out, substantially asherein described.

In testimony whereof I have hereunto set my hand in the presence of twosubscribing witnesses.

BERNHARD DEUTEOOM. [n s] lVitnesses Or'ro KoNIo, WVALTER SLUISKAMP.

